fish8it,
The odds are not in your favor when trying to cool a 36ft long 5th wheel with a single A/C unit.
That said, several members here have checked the a/c flexible ductwork on various models - some
re-taped, or straightened kinks, etc, which helped with air flow. Do a forum search... there's lots
of good advice on this topic. I don't recall who posted, but if memory serves me correctly, some
have even provided photos. Also several threads on adding a 2nd a/c in the bedroom.
Hope this helps!
Terri, the Chevy co-pilot